Question

3)tìm x biết

a) \(\dfrac{x}{7}=\dfrac{18}{14}\)

b) \(6:x=1\dfrac{3}{4}:5\)

c) 5,7:0,35= (-x) :0,45

Answer 1

a/ \(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Leftrightarrow14x=7.18\)

\(\Leftrightarrow14x=126\)

\(\Leftrightarrow x=9\)

Vậy ....

b/ \(6:x=1\dfrac{3}{4}:5\)

\(\Leftrightarrow6:x=\dfrac{7}{20}\)

\(\Leftrightarrow x=\dfrac{120}{7}\)

Vậy ...........

Answer 2

bao giờ bạn cần vậy

nói đi mik giải giùm cho nha!

Answer 3

\(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Rightarrow x=\dfrac{18.7}{14}=9\)

Vậy x=4

Answer 4

Nhầm, vậy x= 9

Answer 5

a. \(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Rightarrow14x=7.18\)

\(\Rightarrow14x=126\Rightarrow x=126:14=9\)

Vậy...

b. \(6:x=1\dfrac{3}{4}:5\)

\(6:x=\dfrac{7}{20}\)

\(x=6:\dfrac{7}{20}=\dfrac{120}{7}\)

Vậy...

c. \(5,7:0,35=\left(-x\right):0,45\)

\(\left(\dfrac{57}{10}\right):\dfrac{7}{20}=\left(-x\right):\dfrac{9}{20}\)

\(\dfrac{114}{7}=\left(-x\right):\dfrac{9}{20}\)

\(\Leftrightarrow\left(-x\right):\dfrac{9}{20}=\dfrac{114}{7}\)

\(\left(-x\right)=\dfrac{114}{7}.\dfrac{9}{20}=\dfrac{760}{21}\)

\(\Rightarrow x=\dfrac{-760}{21}\)

Vậy...

Answer 6

a) \(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Leftrightarrow14x=7.18\)

\(\Leftrightarrow14x=126\)

\(\Leftrightarrow x=9\)

Vậy x = 9

b) \(6:x=1\dfrac{3}{4}:5\)

\(\Leftrightarrow6:x=\dfrac{7}{20}\)

\(\Leftrightarrow x=\dfrac{120}{7}\)

Vậy ...

Answer 7

a/ \(\dfrac{x}{7}\)=\(\dfrac{18}{14}\)

x = \(\dfrac{18.7}{14}\)

x = \(\dfrac{126}{14}\)

x = 9 \(\Rightarrow\) x = 9 b/ 6: x =\(1\dfrac{3}{4}\):5 x = \(\dfrac{6.5}{1\dfrac{3}{4}}\) x = 30 : \(\dfrac{7}{4}\) x = \(\dfrac{120}{7}\) \(\Rightarrow\) x = \(\dfrac{120}{7}\) c/ 5,7:0,35= (-x) :0,45 -x =\(\dfrac{5,7.0,45}{0,35}\) -x =\(\dfrac{2,565}{0,35}\) -x = \(\dfrac{513}{70}\) \(\Leftrightarrow\) x = \(\dfrac{-513}{70}\)

GOOD LUCK !!!

Answer 8

\(\dfrac{x}{7}\)=\(\dfrac{18}{14}\)↔ x.14=7.18→ x=\(\dfrac{7.18}{14}\)=9

b) 6 : x = \(1\dfrac{3}{4}\): 5 ↔ 6 . 5= x .\(1\dfrac{3}{4}\)→ x= \(\dfrac{6.5}{1\dfrac{3}{4}}\)=\(17\dfrac{1}{7}\)

Mik không làm đc ý c) mong bạn thông cảm.

Answer 9

3,

a,\(\dfrac{x}{7}=\dfrac{18}{14}\)

\(\Rightarrow\)x.14=7.18

x.14=126

x = 126:14

x =9

b, 6:x=\(1\dfrac{3}{4}:5\)

\(\Rightarrow\)6.5=x.\(1\dfrac{3}{4}\)

30 =x.\(1\dfrac{3}{4}\)

x =\(\dfrac{7}{4}:30\)

x =\(\dfrac{7}{120}\)

c,5,7:0,35=(-x):0,45

\(\Rightarrow\dfrac{57}{10}:\dfrac{7}{2}=\left(-x\right):\dfrac{9}{20}\)

\(\Rightarrow\)\(\dfrac{57}{10}.\dfrac{9}{20}=\dfrac{7}{2}.\left(-x\right)\)

\(\dfrac{513}{200}=\dfrac{7}{2}.\left(-x\right)\)

-x=\(\dfrac{513}{200}:\dfrac{7}{2}\)

-x=\(\dfrac{74}{100}\)

x=\(\dfrac{-74}{100}\)